commit e57ef2ed97c1d078973298658a8096644a1e9e09
author Thomas Gleixner <tglx@linutronix.de> Thu Sep 15 13:11:01 2022 +0200
committer Peter Zijlstra <peterz@infradead.org> Mon Oct 17 16:41:03 2022 +0200
tree 79cb9a8835ab832a8e8c302abf1ffe0c0ad96c5f
parent fdc9ee7e97aa2c1dfa7ebb092fffec40ffa59108

x86: Put hot per CPU variables into a struct

The layout of per-cpu variables is at the mercy of the compiler. This
can lead to random performance fluctuations from build to build.

Create a structure to hold some of the hottest per-cpu variables,
starting with current_task.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111145.179707194@infradead.org

arch/x86/kernel/process_32.c

diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 2f314b1..807da45 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -207,7 +207,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 	if (prev->gs | next->gs)
 		loadsegment(gs, next->gs);
 
-	this_cpu_write(current_task, next_p);
+	raw_cpu_write(pcpu_hot.current_task, next_p);
 
 	switch_fpu_finish();